This invention relates to cellular mobile telecommunication networks and, in particular, to the provision of a system that enables efficient paging over the wireless communication link with the mobile wireless station set.
It is a problem in the field of cellular mobile telecommunication networks to efficiently provide paging of mobile subscriber stations, since existing protocols do not have a mechanism to address control channel overload conditions.
The processing of a service request in a cellular mobile telecommunication network requires signaling between the mobile subscriber station and the base station. In, for example, the case of a mobile subscriber station registering with a new Mobile Switching Center, messages are passed between the Message Switching Center and the associated Visitor Location Register, the Visitor Location Register and the public network Home Location Register; the Home Location Register/Visitor Location Register in the former visited service area or the mobile subscriber station""s home Mobile Switching Center. The signaling message flow is illustrated in FIG. 2 for a typical ANSI-41 registration activity, focusing only on the essential elements of the message flow relating to registration. Once a terminal enters a new registration area, the mobile subscriber station transmits a registration request to the Mobile Switching Center that serves that area. The Mobile Switching Center transmits an authentication request (AUTHRQST) message to the Visitor Location Register to authenticate the mobile subscriber station which, in turn, transmits the request to the Home Location Register for this mobile subscriber station. The Home Location Register transmits its response back to the Mobile Switching Center in an authentication request response message (authrqst). Assuming that the mobile subscriber station is authenticated, the Mobile Switching Center transmits a registration notification (REGNOT) message to the Visitor Location Register. The Visitor Location Register, in turn, transmits a registration notification (REGNOT) message to the Home Location Register which serves the mobile subscriber station. The Home Location Register updates the location entry corresponding to the mobile subscriber station to point to the new serving Mobile Switching Center Visitor Location Register. The Home Location Register transmits a response back to the Visitor Location Register, which may contain relevant parts of the subscriber""s service profile. The Visitor Location Register stores the service profile in its database and also responds to the serving Mobile Switching Center. If the mobile subscriber station was previously registered in a different mobile subscriber registration area, the Home Location Register transmits a registration cancellation (REGCANC) message to the previously listed Visitor Location Register. On receiving this message, the Visitor Location Register erases all entries for the terminal from the record and transmits a registration cancellation (REGCANC) message to the previously visited Mobile Switching Center, which then erases all entries for the mobile subscriber station from its memory.
Generally, mobile subscriber stations are paged in a full address mode, where the type of paging typically done in this environment is the Long or Extended Mobile Identification Number paging, which occupies a significant bandwidth in the control channel for each paging message transmitted among the system components of the cellular mobile telecommunication network. Presently, this paging operation uses the 24 bit MIN1 (NXX-XXXX) and 10 bit MIN2 (NPA), although different addressing structures are being proposed and implemented such as IMSI with digits 1-9 in the first word and digits 10-15 in the second word. Alternatively, when operating in an area that broadcasts their home System Identification (SID), mobile subscriber stations are able to be paged in a sub-address mode, using a Short MIN paging message that has been developed but is not supported by older existing cellular mobile telecommunication systems, such as those ANSI-41 compatible systems. Both of these noted paging methods work as long as the mobile subscriber station responds with the full address to itself.
The above described problems are solved and a technical advance achieved by the present Mobile Subscriber Station paging system which makes use of a Standalone Home Location Register SHLR, where the mobile subscriber station records are removed from the present Mobile Switching Center and placed on a processor that manages only the subscriber""s records and does not process call service requests. The ANSI-41 standard is then adapted to add a new parameter (CALLTIMEFEATURE) which includes the information required to apply Short MIN paging to a mobile subscriber station when certain conditions are met. These conditions are: the mobile subscriber station is capable of responding to a Short MIN page (the last 24 bits that represent the last 7 digits of the mobile subscriber station number), and the System ID that is immutably entered into the mobile subscriber station is the same as the System ID that is being broadcast by the cell on the overhead message train. When these conditions are met, the paging message can be reduced in length by using a sub-address paging scheme to thereby diminish the control channel overhead. Thus, the last known location of the mobile subscriber station is used in conjunction with the CALLTIMEFEATURE parameter to minimize the length of the paging message. The mobile subscriber station need not be uniquely identified with the complete Mobile Identification Number if its location is known.
FIG. 1 illustrate the overall architecture of a cellular mobile telecommunication network in which the present Mobile Subscriber Station paging system is implemented;
FIG. 2 illustrates the message flow of a control channel message exchange in an existing cellular mobile telecommunication networks;
FIG. 3 illustrates the format of an Abbreviated Address Word used in the control channel of an existing cellular mobile telecommunication networks;
FIG. 4 illustrates the format of an Extended Address Word used in the control channel of an existing cellular mobile telecommunication networks;
FIG. 5 illustrates in flow diagram form, the operation of the present Mobile Subscriber Station paging system in processing a mobile subscriber station registration; and
FIG. 6 illustrates in flow diagram form, the operation of the present Mobile Subscriber Station paging system in processing an incoming call to a mobile subscriber station.